室内海底沉积物热导率测量的原理与方法——以TK04热导率测量系统为例

沉积物热导率是计算海底热流的一个重要参数。文中以TK04热导率测量系统为

Preliminary study of a niobium quarter-wave prototype cavity for a heavy-ion superconducting linac

Superconducting quarter-wave resonators, due to their compactness and their convenient shape for tuning and coupling, are very attractive for low-beta beam acceleration. In this paper, two types of cavities with different geometry have been numerically simulated: the first type with larger capacitive load in the beam line and the second type of lollipop-shape for 100 MHz, beta=0.06 beams; then the relative electromagnetic parameters and geometric sizes have been compared. It is found that the second type, whose structural design is optimized with the conical stem and shaping drift-tube, can support the better accelerating performance. At the end of the paper, some structural deformation effects on frequency shifts and appropriate solutions have been discussed.

番茄专用肥肥效初步研究

番茄专用肥肥效初步研究刘子江，崔桂霞，武冠云（中国科学院沈阳应用生态研究所）赵彩霞，张玉兴王述麟，王阳（沈阳市于洪区畜牧副食局）（沈阳市东陵区畜牧副食局）随着农业生产的发展和科学施肥技术的实施，专用肥的应用愈来愈广泛。专用肥的使用效果，是肥料研究领域...

黄土高原南部3种农田土壤剖面坚实度的变化规律

为了揭示黄土高原南部地区不同质地类型土壤剖面坚实度的变化及其与土壤含水率的定量关系,以黄墡土、土娄土、裸露在地表的粘化层耕作剖面为研究对象,定位观测其0~45 cm土壤坚实度与含水率的变化。结果表明,黄墡土、土娄土、裸露在地表粘化层耕作剖面的犁底层平均坚实度均大于耕层,犁底层平均坚实度较耕层分别高194.8%,87.3%,10.4%;剖面土壤质地越粘其平均坚实度越大;土壤坚实度与含水率呈负相关关系;土壤坚实度变化速率为0时,以上3种土壤剖面临界含水率分别为0.1712,0.1757,0.1835;质地不同的土壤剖面坚实度时空变化特征有差异,其中黄墡土剖面0~20 cm土层土壤坚实度为350~500 kPa,受土壤含水率变化的影响较小;20~30 cm土层土壤的坚实度为500~1400 kPa,不易受外界环境影响;30 cm以下土层土壤坚实度为700~1600 kPa,受土壤含水率变化影响较大。土娄土剖面0~40 cm土层土壤坚实度为600~1200 kPa,受含水率变化影响较大;40 cm以下土层土壤坚实度稳定在1 800 kPa左右。粘化层剖面0~15 cm土层土壤坚实度在2000 kPa左右,受环境影响较...

美国的土壤侵蚀与防治

<正> 美国是世界农业大国,除遇特大自然灾害外,农业生产一直保持长期稳定发展的态势.1990年谷物的生产量达到3.13亿t,预测到2000年谷物产量可达4.53亿t,1985～2000年谷物平均增长速度为1.8%.美国的农业生产之所以能取得如此辉煌的成就有多种原因,其中政府重视土壤保护是最主要的原因之一.80年代初期,美国的农业科学家皮门特尔就曾向全世界发出警告,指出土壤侵蚀已成为全世界第一号环境问题,呼吁人们注意土壤侵蚀给农业生产带来的严重危害.而当时的美国同样面临着土壤侵蚀的严峻形势.深入的研究表明,土壤侵蚀恶性发展的根本原因不在气候变异、水旱等自然灾害,造成土壤侵蚀的根本原因来自人类对自然界的干扰,其中包括不合理的土地利用、滥砍滥伐、破坏森

基于县域要素的三江源地区旅游扶贫模式探讨

随着我国旅游业的兴起,人们越来越认识到旅游在消除贫困上的潜力和能力,然而,要让旅游真正朝着有利于消除贫困的方向发展,必须对旅游的发展方式加以调整,因地制宜地选择旅游扶贫的模式。本文构建了三江源地区各县贫困程度和旅游资源禀赋评价指标体系,定量测度了各评价区的贫困度和旅游资源禀赋综合得分,并采用四象限法划分出资高贫低、双高、双低、资低贫高4种旅游扶贫类型区,在此基础上,提出适用于整个三江源地区的旅游扶贫基本模式为政府主导模式,以及各类型区的旅游扶贫辅助模式,即资高贫低区的政企合作模式,双高区的项目推动模式,双

Synthesis and characterization of white-light-emitting polyfluorenes containing orange phosphorescent moieties in the side chain

Two orange phosphorescent iridium complex monomers, 9-hexyl-9-(iridium (III)bis(2-(4'-fluorophenyl)-4-phenylquinoline-N, C-2')(tetradecanedionate-11,13))-2,7-dibromofluorene (Br-PIr) and 9-hexyl-9-(iridium(III)bis(2-(4'-fluorophenyl)-4-methylquinoline-N, C-2')(tetradecanedionate-11,13))-2,7-dibromofluorene (Br-MIr), were successfully synthesized. The Suzuki polycondensation of 2,7-bis(trimethylene boronate)-9,9-dioctylfluorene with 2,7-dibromo-9,9-dioetylfluorene and Br-Plr or Br-MIr afforded two series of copolymers, PIrPFs and MIrPFs, in good yields, in which the concentrations of the phosphorescent moieties were kept small (0.5-3 mol % feed ratio) to realize incomplete energy transfer. The photoluminescence (PL) of the copolymers showed blue- and orange-emission peaks. A white-light-emitting diode with a configuration of indium tin oxide/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/PIr05PF (0.5 mol % feed ratio of Br-PIr)/Ca/Al exhibited a luminous efficiency of 4.49 cd/A and a power efficiency of 2.35 lm/W at 6.0 V with Commission Internationale de L'Eclairage (CIE) coordinates of (0.46, 0.33). The CIE coordinates were improved to (0.34, 0.33) when copolymer MIr10PF (1.0 mol % feed ratio of Br-MIr) was employed as the white-emissive layer. The strong orange emission in the electroluminescence spectra in comparison with PL for these kinds of polymers was attributed to the additional contribution of charge trapping in the phosphorescent dopants.